A method for constructing directional surface wave spectra from ICESat-2 altimetry
Sea ice is important for Earth's energy budget as it influences surface albedo and air–sea fluxes in polar regions. On its margins, waves heavily impact sea ice. Routine and repeat observations of waves in sea ice are currently lacking, and therefore a comprehensive understanding of how waves i...
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ftdoajarticles:oai:doaj.org/article:5056d816b66744a1b92064c8973f6a05 2024-02-11T10:08:29+01:00 A method for constructing directional surface wave spectra from ICESat-2 altimetry M. C. Hell C. Horvat 2024-01-01T00:00:00Z https://doi.org/10.5194/tc-18-341-2024 https://doaj.org/article/5056d816b66744a1b92064c8973f6a05 EN eng Copernicus Publications https://tc.copernicus.org/articles/18/341/2024/tc-18-341-2024.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-18-341-2024 1994-0416 1994-0424 https://doaj.org/article/5056d816b66744a1b92064c8973f6a05 The Cryosphere, Vol 18, Pp 341-361 (2024) Environmental sciences GE1-350 Geology QE1-996.5 article 2024 ftdoajarticles https://doi.org/10.5194/tc-18-341-2024 2024-01-21T01:35:45Z Sea ice is important for Earth's energy budget as it influences surface albedo and air–sea fluxes in polar regions. On its margins, waves heavily impact sea ice. Routine and repeat observations of waves in sea ice are currently lacking, and therefore a comprehensive understanding of how waves interact with sea ice and are attenuated by it is elusive. In this paper, we develop methods to separate the two-dimensional (2D) surface wave spectra from sea-ice height observations made by the ICESat-2 (IS2) laser altimeter, a polar-orbiting satellite. A combination of a linear inverse method, called generalized Fourier transform (GFT), to estimate the wave spectra along each beam and a Metropolis–Hastings (MH) algorithm to estimate the dominant wave's incident angle was developed. It allows us to estimate the 2D wave signal and its uncertainty from the high-density, unstructured ATL03 ICESat-2 photon retrievals. The GFT is applied to re-binned photon retrievals on 25 km segments for all six beams and outperforms a discrete Fourier transform (DFT) in accuracy while having fewer constraints on the data structure. The MH algorithm infers wave direction from beam pairs every 25 km using coherent crests of the most energetic waves. Assuming a dominant incident angle, both methods together allow a decomposition into 2D surface wave spectra with the advantage that the residual surface heights can potentially be attributed to other sea-ice properties. The combined GFT–MH method shows promise in routinely isolating waves propagating through sea ice in ICESat-2 data. We demonstrate its ability on a set of example ICESat-2 tracks, suggesting a detailed comparison against in situ data is necessary to understand the quality of retrieved spectra. Article in Journal/Newspaper Sea ice The Cryosphere Directory of Open Access Journals: DOAJ Articles Hastings ENVELOPE(-154.167,-154.167,-85.567,-85.567) The Cryosphere 18 1 341 361 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 M. C. Hell C. Horvat A method for constructing directional surface wave spectra from ICESat-2 altimetry |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Sea ice is important for Earth's energy budget as it influences surface albedo and air–sea fluxes in polar regions. On its margins, waves heavily impact sea ice. Routine and repeat observations of waves in sea ice are currently lacking, and therefore a comprehensive understanding of how waves interact with sea ice and are attenuated by it is elusive. In this paper, we develop methods to separate the two-dimensional (2D) surface wave spectra from sea-ice height observations made by the ICESat-2 (IS2) laser altimeter, a polar-orbiting satellite. A combination of a linear inverse method, called generalized Fourier transform (GFT), to estimate the wave spectra along each beam and a Metropolis–Hastings (MH) algorithm to estimate the dominant wave's incident angle was developed. It allows us to estimate the 2D wave signal and its uncertainty from the high-density, unstructured ATL03 ICESat-2 photon retrievals. The GFT is applied to re-binned photon retrievals on 25 km segments for all six beams and outperforms a discrete Fourier transform (DFT) in accuracy while having fewer constraints on the data structure. The MH algorithm infers wave direction from beam pairs every 25 km using coherent crests of the most energetic waves. Assuming a dominant incident angle, both methods together allow a decomposition into 2D surface wave spectra with the advantage that the residual surface heights can potentially be attributed to other sea-ice properties. The combined GFT–MH method shows promise in routinely isolating waves propagating through sea ice in ICESat-2 data. We demonstrate its ability on a set of example ICESat-2 tracks, suggesting a detailed comparison against in situ data is necessary to understand the quality of retrieved spectra. |
format |
Article in Journal/Newspaper |
author |
M. C. Hell C. Horvat |
author_facet |
M. C. Hell C. Horvat |
author_sort |
M. C. Hell |
title |
A method for constructing directional surface wave spectra from ICESat-2 altimetry |
title_short |
A method for constructing directional surface wave spectra from ICESat-2 altimetry |
title_full |
A method for constructing directional surface wave spectra from ICESat-2 altimetry |
title_fullStr |
A method for constructing directional surface wave spectra from ICESat-2 altimetry |
title_full_unstemmed |
A method for constructing directional surface wave spectra from ICESat-2 altimetry |
title_sort |
method for constructing directional surface wave spectra from icesat-2 altimetry |
publisher |
Copernicus Publications |
publishDate |
2024 |
url |
https://doi.org/10.5194/tc-18-341-2024 https://doaj.org/article/5056d816b66744a1b92064c8973f6a05 |
long_lat |
ENVELOPE(-154.167,-154.167,-85.567,-85.567) |
geographic |
Hastings |
geographic_facet |
Hastings |
genre |
Sea ice The Cryosphere |
genre_facet |
Sea ice The Cryosphere |
op_source |
The Cryosphere, Vol 18, Pp 341-361 (2024) |
op_relation |
https://tc.copernicus.org/articles/18/341/2024/tc-18-341-2024.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-18-341-2024 1994-0416 1994-0424 https://doaj.org/article/5056d816b66744a1b92064c8973f6a05 |
op_doi |
https://doi.org/10.5194/tc-18-341-2024 |
container_title |
The Cryosphere |
container_volume |
18 |
container_issue |
1 |
container_start_page |
341 |
op_container_end_page |
361 |
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1790607837739614208 |